1. Field of the Invention
The present invention relates to systems and methods for embedding data in electronic signals More particularly, the present invention relates to systems and methods for embedding data in a dial tone signal that is provided by a private branch exchange telephone system.
2. Present State of the Art
The telephone, in its simplest form, is a device used to carry the voice communications of one person to another person. Telephones have become an indispensable part or our lives and can be found in practically every home, in businesses, on airplanes, and on almost every street corner. The widespread use of telephones has made them easily accessible and they are in almost constant use.
The telephone was originally conceived to carry voice communications and it has served that function well. Today, any one telephone can typically be connected to any other telephone. The Public Switched Telephone Network (PSTN), which is the network connecting telephones to each other, therefore plays a primary role in our use of telephones. The PSTN provides dial tones, ringing signals, call waiting signals and other amenities for our use and enjoyment.
In order to effectively allow voice communication to occur over a telephone, a set of standards was developed which correspond to a set of states within which a telephone operates. The states correspond to actions performed by a telephone as well as to actions performed by the central office or the PSTN. States also correspond to actions occurring over the electronic signals that are received and transmitted over the PSTN.
The central office applies various AC and DC voltages to a two wire phone loop consisting of two wires known as the xe2x80x9ctipxe2x80x9d and xe2x80x9cring.xe2x80x9d The AC and DC voltages applied to the tip and ring are indicative of the various states that a telephone may occupy. When a telephone is not being used, it is in an idle state or xe2x80x9con hook.xe2x80x9d During the idle state, the central office applies a DC voltage to the phone loop, but very little current actually flows through the phone loop because a telephone is designed to have a certain impedance when it is on hook. The impedance has a large magnitude and effectively prevents current from flowing through the phone loop. When the telephone is taken off hook or in a dialing state, the impedance drops dramatically and a more significant current begins to flow through the phone loop. The central office senses this current flow and provides the user with a dial tone.
The dial tone indicates to a user that a number may be dialed and once a number has been dialed by a user, the ring state begins. During the ring state, the central office or PSTN applies an AC ringing signal to the tip and ring. The ring signal may occur, for example, at two second bursts over a six second interval. When a person answers a telephone that is ringing, the talking state begins and the voice or analog signals are carried on the PSTN between the persons that are connected by the PSTN.
The telephone network has grown to accommodate millions of people and in order to insure that all people receive proper service, the PSTN is subject to a number of different regulations. The regulations describe the specifications that any device connecting to the PSTN must meet, thus ensuring that the PSTN will not be adversely affected by the attachment of a connecting device. In addition to the specifications of connecting devices, the PSTN is itself subject to specific standards. Some of these specifications and standards it relate to the level of the DC and AC voltages, the frequency of the ringing signal and the frequency of the dial tone. These standards are strict and may not be altered by a user or a connecting device.
While these specifications ensure that the PSTN will function properly, many businesses and organizations are faced with the problem of providing telephone service to all the telephones existing within their enterprise. The PSTN would indicate that a phone loop must be established with each. and every telephone. For businesses and organizations having thousands of telephones, this is a significant logistical and economical problem.
The solution to this particular problem was the development of a private branch exchange (PBX) telephone system A PBX is a private telephone network that is used within a business or organization such as a large corporation or a hotel. A PBX is much less expensive than installing an external telephone line to each telephone within the organization. In addition, the people connected to a particular PBX telephone system can communicate with one another much easier because fewer numbers must be dialed in order to reach another person in the same PBX system.
PBX systems provide flexibility to an organization and may be digital or analog in nature. The PBX system allows many persons to have access to the PSTN without having to connect an external phone line to each telephone. The PBX system is, in effect, emulating the central office and as a result, the PBX system is typically required to meet the specifications that are prescribed by the central office. In other words, when a person utilizing a PBX system picks up a telephone connected to the PBX system, a dial tone similar to the dial tone of the PSTN is presented over the PBX system Modems and other connecting devices are typically designed to meet the specifications of the PSTN and in order for those devices to function within a PBX system, the PBX should provide the voltages and signals that are present on the PSTN.
The installation of a PBX system allows users of the PBX system to access the PSTN. This is important for many users and is especially important for persons that are away from their normal computer network connections. For example, users frequently need access to the Internet when they are traveling and many of those travelers stay in hotels which typically have PBX systems installed. The capability to use PBX systems is often essential to the traveling user. Laptop computers equipped with moderns are often used to connect to the PSTN through a PBX system
The problem the user faces at this point is knowing what numbers to dial in order to reach a remote location. For example, the user may subscribe to an Internet service provider that has a local access number for many different locations. When the user is traveling, the local access number of the city where the traveler is staying cannot be used because the traveler does not know that number. The local access number of the user""s home can be used but the user will most likely incur the expense of a long distance telephone call. The user may not be aware of the area code of the telephone line being used, or what the charges are for calls made by a modem or the number to dial to reach an outside line. In many instances, this and other relevant data is not readily accessible to a user.
It would be an advance in the art to provide the user over a modem with data which is readily accessible over a PBX system or other telephone system without interfering with the standards promulgated by the PSTN.
PBX and other telephone systems are used by many different organizations and businesses to allow a large group of persons access to the PSTN. Many PBX systems, such as those found in hotels, are made available to many different persons. In today""s society, PBX systems are being increasingly used for modem connections. The methods and systems of the present invention provide the user with useful access information which can be downloaded or retrieved from a premise PBX system using the modem without any additional hardware.
A PBX system is similar to the PSTN or central office in the sense that it emulates the central office. Connection devices such as modems and telephones that connect to a PBX system view the PBX system as the central office because the PBX provides the same signals to the connection devices that the central office would otherwise provide. A difference between the central office and a PBX or centrex system is that the signals provided by the central office cannot be altered or changed whereas the signals provided by the PBX system can be altered without having an adverse effect on either the central office or the connection devices connected to the PBX system
In many situations, people that connect with a PBX system do not have easy access to vital information such as call billing information, the local area code, and the number of the telephone line in use. The present invention provides systems and methods for providing a user with access information, which may include information that the user may find useful. The access information is embedded, in one embodiment, in the dial tone generated and provided by the PBX system. The access information is embedded when the amplitude of the dial tone is small such that the audible quality of the dial tone is essentially unaffected. Connection devices such as moderns are able to listen to the dial tone and detect and extract the embedded access information from the dial tone.
In one embodiment, a modern is configured to go automatically go off hook when a user connects the modem to the PBX system While the modem is off hook, the dial tone containing embedded access information is received by the modem The access information is detected, extracted and displayed to the user. At this point, the modem goes on hook and waits for further user instruction. Alternatively, the modem may immediately use the information. For instance, if the telephone number of an Internet service provider is included in the access information, the modem may immediately dial that number.
Additional objects and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other objects and features of the present invention will become more fly apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.